How did you create a startup program? I did the xinput set-prop 11 121 0 and itworked for me as well
(I had to change mine to 11, beacuse 11 was the ID instead of 12)
How do you make like a file on linux so that it will run that code every time I turn on my pc and load linux? If you do not understand what I mean, I am asking like how you make a batch file but for Linux.